Participants in the trial will first notice a kind of instant-search feel to Gmail search results, as relevant e-mails will begin popping up in the search bar as soon as users start typing. And it won't only be e-mail: The trial lets users search Google Drive and Google Calendar as well.

The trial also expands personal search options on Google.com, bringing in documents, spreadsheets and other files from Google Drive into search results.

"When you're looking for something, you should be able to find what you need quickly and easily without needing to think about where it might be, whether it's in your email or out on the public web," Google's Bram Moolenaar said in a blog post.

To join the trial, visit this page and click the button signifying you wish to join. Note that this trial works only with Gmail addresses; Google Apps users will have to wait a bit.

Personal search raises some legitimate privacy concerns. Someone using Google to run searches on a shared computer could see Gmail results from a logged-in user. That's why it's likely to remain an opt-in kind of service for the foreseeable future.